(a) Field of the Invention
The present invention relates to a cylindrical pump device having a flexible blade member and, more particularly, to a cylindrical pump device suitably used in an ink jet recording device.
(b) Description of the Related Art
In an ink jet recording device, after discharging liquid ink for a certain amount of time in succession, bubbles are formed in an ink passage in the ink jet recording head. The bubbles become obstacles against the discharge of the liquid ink from the nozzle of the recording head to thereby degrade the printing quality of the ink jet recording device. To avoid such a degradation in the printing quality, a pump system is generally installed in the ink jet recording device to discharge, periodically or upon request, the bubbles together with the liquid ink from the ink jet recording head.
A conventional pump system such as shown in FIG. 1 is generally used in an ink jet recording device. The pump system is installed between an ink jet recording head 12 and an ink reservoir 21, and includes a plunger pump 11 and a pair of valves 13 and 15 disposed between the inlet port of the plunger pump 11 and the ink jet recording head 12 and between the outlet port of the plunger pump 11 and the ink reservoir 21, respectively.
In operation, the plunger pump 11 is first started for operation with the inlet valve 13 and outlet valve 15 being closed and opened, respectively, to allow the air remaining in the plunger pump 11 to be discharged to the ink reservoir 21 through tubes 19 and 20. The pump 11 is stopped, and then restarted after inlet valve 13 and outlet valve 15 are opened and closed, respectively, to pull out the bubbles together with liquid ink in the nozzle of the recording head 12 through the tube 16 and 17 to the pump 11. Then, the pump 11 is again stopped, and restarted after inlet valve 13 and outlet valve 15 are closed and opened, respectively, to allow the bubbles and liquid ink to be discharged to the ink reservoir 21. The operations are periodically repeated for several times to discharge the bubbles together with the liquid ink from the ink jet recording head 12 to the ink reservoir 21.
The conventional pump system as used in an ink jet recording head has a disadvantage that the pump system has a complicated configuration due to the pair of valves and suffers from a complicated operation, as described above.